Is a low transfusion threshold safe in critically ill patients with cardiovascular diseases?

Objective: To compare a restrictive red blood cell transfusion strategy wit h a more liberal strategy in volume-resuscitated critically ill patients wi th cardiovascular disease. Setting: Twenty-two academic and three community critical care units across Canada. Study Design: Randomized controlled clinical trial. Study Population: Three hundred fifty-seven critically ill patients with ca rdiovascular diseases from the Transfusion Requirements in Critical Care tr ial who had a hemoglobin concentration of <90 g/L within 72 hrs of admissio n to the intensive care unit. Interventions: Patients were randomized to a restrictive strategy to receiv e allogeneic red blood cell transfusions at a hemoglobin concentration of 7 0 g/L (and maintained between 70 and 90 g/L) or a liberal strategy to recei ve red blood cells at 100 g/L land maintained between 100 and 120 gill. Results: Baseline characteristics in the restrictive (n = 160) and the libe ral group (n = 197) were comparable, except for the use of cardiac and anes thetic drugs (p < .02), Average hemoglobin concentrations (85 +/- 6.2 vs. 1 03 +/- 6.7 g/L; p < .01) and red blood cell units transfused (2.4 +/- 4.1 v s. 5.2 +/- 5.0 red blood cell units; p < .01) were significantly lower in t he restrictive compared with the liberal group. Overall, all mortality rate s were similar in both study groups, including 30-day (23% vs. 23%; p 1.00) , 60-day, hospital, and intensive care unit rates. Changes in multiple orga n dysfunction from baseline scores were significantly less in the restricti ve transfusion group overall (0.2 +/- 4.2 vs. 1.3 +/- 4.4; p = .02). In the 257 patients with severe ischemic heart disease, there were no statistical ly significant differences in all survival measures, but this is the only s ubgroup where the restrictive group had lower but nonsignificant absolute s urvival rates compared with the patients in the liberal group. Conclusion: A restrictive red blood cell transfusion strategy generally app ears to be safe in most critically ill patients with cardiovascular disease , with the possible exception of patients with acute myocardial infarcts an d unstable angina.